In gas turbine engines, air from a compressor section and fuel from a fuel supply are mixed together and burned in a combustion section. The products of combustion flow through a turbine section, where they expand and turn a central shaft. In a can-annular combustor configuration, a circular array of combustors is mounted around the turbine shaft. Each combustor may have a central pilot burner surrounded by a number of main fuel injectors. A central pilot flame zone and a main fuel/air mixing region are formed. The pilot burner produces a stable flame, while the injectors deliver a stream of mixed fuel and air that flows past the pilot flame zone into a main combustion zone. Energy released during combustion is captured downstream by turbine blades, which turn the shaft.
In order to ensure optimum combustor performance, it is preferable that the respective fuel-and-air streams are well mixed to avoid localized, fuel-rich regions. As a result, efforts have been made to produce combustors with essentially uniform distributions of fuel and air. Swirler elements are used to produce a stream of fuel and air in which air and injected fuel are evenly mixed. Within such swirler elements are holes releasing fuel supplied from manifolds designed to provide a desired amount of a given fluid fuel, such as fuel oil or natural gas.
Fuel availability, relative price, or both may be factors for an operation of a gas turbine, so there is an interest not only in efficiency and clean operation but also in providing fuel options in a given turbine unit. Consequently, dual fuel devices are known in the art.
Synthetic gas, or syngas, is gas mixture that contains varying amounts of carbon monoxide and hydrogen generated by the gasification of a carbon-containing fuel such as coal to a gaseous product with a heating value. Modern turbine fuel system designs should be capable of operation not only on liquid fuels and natural gas but also on synthetic gas, which has a much lower BTU (British Thermal Unit) energy value per unit volume than natural gas. This criterion has not been adequately addressed. Thus, there is a need for a flex-fuel mixing device that provides efficient operation using fuels with low energy density, such as syngas, as well as higher energy fuels, such as natural gas.